Cermet Electrolyte Anode-Supported SOFC Thermal Mismatch

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Solution Overview

Problem

Anode-supported solid oxide fuel cells (SOFCs) face challenges with superior electrochemical performance and structural reliability due to thermal expansion coefficient mismatch between the anode cermet and conventional ceramic electrolyte, leading to cell failure during fabrication and operation.

Innovation Solution

The introduction of a cermet electrolyte with a minor metal phase dispersed throughout a ceramic material, allowing for increased metal content in the anode and reduced thermal expansion coefficient mismatch, along with the use of transition metals like Ni, Co, and Cu, and ceramic materials like stabilized-zirconia and doped-ceria, to enhance electrical conductivity and mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional ceramic electrolyte is used in an anode-supported SOFC, then the cell structure can be formed, but thermal expansion coefficient mismatch causes cell failure during fabrication and operation

Engineering Contradiction:

Improvecell structural reliabilityVSAvoidthermal expansion coefficient mismatch

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies composite materials by creating a cermet electrolyte that combines ceramic material (for ionic conductivity) with metal particles (for mechanical strength and thermal expansion matching). This composite structure resolves the thermal expansion mismatch between the anode and electrolyte while maintaining the necessary electrochemical performance, preventing cell failure during fabrication and operation.

Inventive Principle:

Principle #40Composite materials

2Power

If metal content in the anode is increased to enhance electrical conductivity, then power density improves, but thermal expansion coefficient mismatch with ceramic electrolyte worsens

Engineering Contradiction:

Improvepower densityVSAvoidthermal expansion coefficient mismatch

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The cermet electrolyte combines ceramic and metal phases, allowing the anode to have high metal content for electrical conductivity while the electrolyte's ceramic matrix maintains dimensional stability. The metal particles dispersed in the ceramic electrolyte create a graded thermal expansion profile that accommodates high metal content in the anode without causing mismatch failures.

Inventive Principle:

Principle #40Composite materials

3Temperature

If electrochemical vapor deposition is used to deposit thin electrolyte films, then high efficiency and lower operating temperature are achieved, but manufacturing cost increases significantly

Engineering Contradiction:

Improveoperating temperatureVSAvoidmanufacturing cost

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters by using a cermet electrolyte with optimized metal-to-ceramic ratios and controlled particle size distribution. This allows the electrolyte to achieve the necessary ionic conductivity at lower operating temperatures through compositional modification rather than requiring expensive advanced deposition techniques, maintaining high efficiency while reducing manufacturing costs.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach results in improved mechanical reliability and high power density SOFCs with reduced processing steps and costs, maintaining structural integrity and electrochemical performance across a range of temperatures.

Implementation Method 1

Oxygen is converted at the cathode to oxygen ions, which diffuse through the membrane and react with the fuel at the anode

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

reduced thermal expansion coefficient mismatch between the anode cermet and the conventional ceramic electrolyte

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

use of transition metals like Ni, Co, and Cu, and ceramic materials like stabilized-zirconia and doped-ceria, to enhance electrical conductivity

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS7498095B2Anode-supported solid oxide fuel cells using a cermet electrolyte

Publication Date: 2009.03.03 WATT FUEL CELL CORP

AI summary

Novel solid oxide fuel cell (SOFC) article and method of manufacture with improved properties at lower costs. The structural features and methods involve fabricating an anode (i.e., fuel electrode); applying a cermet electrolyte, which includes a mixture of ceramic and electrochemically active substances, and applying a cathodic layer. The cermet electrolyte containing a small amount of transition metal reduces the thermal expansion mismatch with the anode, and allows for a graded structure of the electrochemically active substances across the anode/electrolyte structure. Under operating conditions, a dense electrolyte and metal oxide sub-layer exist on the oxidized side (cathode side); while the other side of the electrolyte (reducing side) is made of a porous sub-layer containing transition metal. The tailoring of the amounts of metal present in the anode and the cermet electrolyte allows for greater power output and enhanced electrochemical performance, while maintaining the structural integrity and reliability of the SOFC.